Commercial products having imaging capability, such as computer printers, graphics plotters, facsimile machines, etc., have been implemented with fluid-ejection devices producing printed media. In many cases, such devices utilize inkjet technology whereby an inkjet image is created when a precise pattern of dots is formed on a printing medium from ejected ink droplets. Typically, an inkjet print head is supported on a movable carriage that traverses over the surface of the print medium and is controlled to eject drops of ink at appropriate times pursuant to commands of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to a pattern of pixels of the image being printed. A typical inkjet print head includes an array of precisely formed nozzles in an orifice plate. The plate is attached to a thin-film substrate that implements ink firing heater resistors and apparatus for enabling the resistors. The thin-film substrate is generally comprised of several thin layers of insulating, conducting, or semiconductor material that are deposited successively on a supporting substrate, or die, in precise patterns to form collectively, all or part of an integrated circuit.
The thin-film substrate or die is typically comprised of a layer, such as silicon, on which are formed various thin-film layers that form thin-film ink firing resistors, apparatus for enabling the resistors, and interconnections to bonding pads that are provided for external electrical connections to the print head. Ongoing improvements in the design of fluid-ejection devices have resulted in more efficient print-head components, such as resistors barrier layers, and passivation layers. In some cases, barrier layers and passivation layers deposited by physical vapor deposition or chemical vapor deposition methods have been utilized to improve performance. In other cases; sputtering techniques have been used to form barrier layers and passivation layers. While these techniques have some utility, it is desirable to have an improved barrier layers and passivation layers capable of improving performance and increasing resistor life.
Of course, energy expenditure is necessary for operation of fluid-ejection devices. In this regard, the term “turn-on energy” relates to the energy required to form a vapor bubble of a size sufficient to eject a predetermined amount of ink volume through a print head nozzle. With ever increasing usage of electrically driven devices, conservation becomes an important consideration. With respect to fluid-ejection devices, a reduction in “turn-on energy” would be desirable, especially if such reduction produced improved print head performance and prolonged print head life.